Genetics of Hereditary Hearing Loss in the Middle East: A Systematic Review of the Carrier Frequency of the GJB2 Mutation (35delG)

Background and Objectives: Mutations in the GJB2 gene are a major cause of hearing loss in many populations. A single mutation of this gene (c.35delG) accounts for approximately 70% of mutations in Caucasians with a carrier frequency of 2-4% in Europe. This study aims to determine the rate of c.35delG carrier frequency in the Middle East. Method: A systematic literature review of the PubMed, Google Scholar, Web of Science, and Science Direct databases was conducted for articles published before March 2019. The primary data of eligible studies including the number of samples, carrier frequency and so on were extracted. Results: Fourteen studies that involved 5,200 random controls from 15 populations of the Middle East were included and analyzed for the carrier frequency. The overall c.35delG carrier frequency was found to be 1.38% in the studied populations which is significantly lower than that identified in European populations, and also a west-to-east Middle Eastern gradient in the carrier frequency of c.35delG is suggested. Conclusion: This study shows the importance of establishing prevalence, based on the local population, for screening and diagnostic programs of live births.